Solution:

A body that emits radiation at all possible wavelengths and absorbs all incident radiation, regardless of the wavelength or direction, is known as a perfect blackbody.

Explanation:

A perfect blackbody is an idealized object in thermodynamics and physics that has the following properties:

1. Perfect Absorber: It absorbs all radiation that falls on it, meaning it doesn't reflect or transmit any radiation. This is why it appears perfectly black.
2. Perfect Emitter: A blackbody is also the most efficient emitter of thermal radiation. At any given temperature, it emits the maximum amount of energy possible for that temperature across all wavelengths.

The radiation emitted by a blackbody is described by Planck's law and is dependent only on the body's temperature. The distribution of wavelengths emitted by a blackbody follows a characteristic curve, with the peak wavelength shifting according to Wien's displacement law as the temperature changes. The total energy emitted by the blackbody is given by the Stefan-Boltzmann law.

Examples:

• A perfect blackbody doesn't exist in the real world, but certain objects can approximate blackbody behavior. For instance, a small hole in a cavity acts like a nearly perfect blackbody because any radiation entering the hole is unlikely to escape.
• The Sun is often approximated as a blackbody in physics, though it's not perfect, it emits a nearly continuous spectrum of light.

Thus, a perfect blackbody is an ideal concept used to study and understand radiation emission and absorption.